Immune function
There is an extensive body of basic science dealing with the role of vitamin D in various aspects of the immune response.
2,3 At a clinical level, it has long been recognized that rickets in children was associated with increased risk of respiratory infection, and that the cause of death in rachitic children was commonly pneumonia. Two recent, randomized, controlled trials help to extend these observations to adult humans. In one, Nursyam et al.
25 showed a highly significant improvement in response to standard anti-tubercular therapy in a group of patients with pulmonary tuberculosis who were randomly allocated to receive a placebo or 10,000 IU vitamin D per day, a dose that would typically produce a serum 25(OH)D level in the range of 200–220 nmol/L.
26 Aloia et al.,
27 in a randomized controlled trial of 208 African American women, showed a 70% reduction in the occurrence of serious respiratory infections (including influenza) in the group treated with up to 2000 IU vitamin D per day. In these women, serum 25(OH)D was raised from 46.9 to 86.9 nmol/L.
